It is known to provide vacuum cleaners with cyclonic separating apparatus for separating dirt and dust from an airflow. It is also known to provide such separating apparatus with two cyclones arranged in series, the upstream cyclone being of relatively low efficiency and the downstream cyclone being of higher efficiency. Such an arrangement is shown and described in EP 0 042 723. It has been found to be beneficial if a so-called shroud is positioned at the outlet to the upstream cyclone in such an arrangement. This positioning of the shroud 10, as has been adopted in vacuum cleaners manufactured and sold by Dyson Limited, is illustrated in FIGS. 1a and 1b. 
A shroud is commonly formed by providing a wall having a large number of perforations or through-holes which communicate on their upstream side with the separating chamber of the upstream cyclone. The through-holes of the shroud thus form the outlet from the separating chamber. However, as dirt- and dust-laden air is pulled through the shroud, there is a risk that some of the entrained dirt and dust could clog some of the through-holes whilst long, lightweight matter, such as hairs and threads, can become wrapped around the shroud. Blocking the through-holes of the shroud can reduce the efficiency at which the vacuum cleaner operates.
In order to maximise the amount of dirt and dust retained in the separating chamber upstream of the shroud, known shrouds have been provided with a depending lip which projects into the separating chamber. Such a lip is shown and described in EP 0 800 359. This lip has a beneficial effect on the separating apparatus in which the shroud is used in that the risk of the shroud through-holes becoming clogged or blocked is reduced.